ATLANTA -- The Atlanta Braves, who struggled against the team with the best record in the National League, are off to a much better start vs. the American League club with the top record.

The Braves slugged four homers and opened an interleague series against the Oakland Athletics with a 7-2 victory Friday night before a crowd of 30,606 at Turner Field.

Rookie Phil Gosselin, filling in at shortstop for Andrelton Simmons, connected for his first homer in the majors against reliever Jesse Chavez in the sixth inning after left fielder Justin Upton, catcher Evan Gattis and first baseman Freddie Freeman had connected off starter Jason Hammel.

It was the fourth time this year the Braves had hit four homers in a game and the second time in eight days.

"April, May you think it's a marathon," manager Fredi Gonzalez said of the season slipping away from the Braves. "Now it's a sprint and we have to get going."

Hammel, who was 8-5 with a 2.98 ERA for the Chicago Cubs, fell to 1-5 with a 6.75 ERA for Oakland since his acquisition in early July.

The victory kept Atlanta (62-60) from falling to .500 after going 1-6 against the NL-best Los Angeles Dodgers in the past two weeks. Oakland (73-49) still has the best record in the AL despite a 1-5 stretch.

Freeman's home run was a three-run blast and Gosselin's two-run homer to center field came on a first-pitch cutter from Chavez after an error had prolonged the sixth inning.

Gosselin, who had earlier filled in at second and third, is now 6-for-21 since being called up from Triple-A Gwinnett, where he was hitting .344.

"It's nice to have that piece you can run out there," Gonzalez said.

The only homer that Gosselin could remember even coming close to this one came for the University of Virginia against Stephen Strassburg of San Diego State in the NCAA Tournament.

"This one's on a bigger stage," Gosselin said. "It felt awesome."

Gosselin's first homer apparently slipped up on his teammates, who did try the silent treatment or anything.

"I don't know why we didn't," Freeman said.

Braves starter Alex Wood (9-9) worked six innings, allowing four hits, and the two runs against him came on a homer by Nate Freiman. The left-hander walked three and struck out one, leaving after 96 pitches.

Wood had thrown 124 pitches and struck out 12 in a victory over Washington last Sunday, giving up five hits and a run over 7 1/3 innings.

"With four homers, I don't know anyone wants to talk to me," Wood said. "It was like old times offensively."

After going 0-4 with 9.53 ERA is his first four games with Oakland, Hammel was 1-0 with a 0.75 ERA in his next two starts before struggling again against the Braves.

Upton and Gattis smashed homers a batter apart in the second inning, both connecting on second-pitch fastballs that Hammel left in their wheelhouses. It was Upton's 22nd home run and Gattis' 18.

Then Freeman connected for a three-run blast in the third inning, picking on a hanging 0-1 slider and smacking a drive over the center-field fence for his 17th homer of the year.

Hammel was pulled after issuing a leadoff walk in the fourth inning. He gave up six hits, walked one, hit a batter and struck out two while throwing 60 pitches. The three homers he gave up raised his total to nine in just 32 innings with the A's.

"I've got to keep the ball in the yard," Hammel said. "That's the bottom line. Two fastballs that were outer third that were hittable and then a slider to Freeman with guys on base. Three-run homers do some damage, solo homers you can deal with. That third one was obviously a big one, so once again, the execution on those three pitches just wasn't good."

Wood gave the two-run homer to Freiman in the fourth inning, the first baseman connecting on a 3-1 fastball immediately after a leadoff double by Derek Norris. It was Freiman's second homer of the year.

The last 17 Oakland batters were retired, with relievers David Carpenter, Jordan Walden and James Russell each pitching a perfect inning behind Wood.

NOTES: Braves SS Andrelton Simmons was out of the starting lineup because of an abscessed tooth. ... SS Andy Parrino, called up from Triple-A Sacramento when SS Jed Lowrie went on the disabled list, got a start for Oakland. ... The Braves and A's hadn't played since 2008. Two of the three previous interleague matchups were also in Atlanta, and the Braves held a 5-4 series edge coming into this season. ... The A's had won 10 of their previous 12 interleague games this year, while the Braves were just 4-10. ... RHP Sonny Gray (12-6, 2.86 ERA) will start for Oakland in the middle game of the series Saturday night against RHP Julio Teheran (10-9, 3.06 ERA) of the Braves. ... Sunday's game was moved to 8:05 p.m. for ESPN. The A's haven't been on the ESPN's Sunday Night telecast since 2006.